you're under alot of stress at the moment, so you obviously need to talk to someone. could you talk to your partner about how your feeling?
i'm not sure its a good idea if you tell your cousin because you might be putting her in an awkward position and she might think twice about being around you whilst shes pregnant if she knows its upsetting to you.
your not alone in this, you have you partner. tell him how you feel. if your stressing about things, then that will make getting pregnant even harder (so I've heard).
it will happen in time. you've already done it once (your daughter), so it shows you can do it, its just a matter of time!